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  #1  
Old 02-06-2009, 11:03 PM
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Question No oil cap = Alternator not working??

What's the possibility of an alternator shorting out if it's saturated with motor oil?
My wife added oil in our 1990 300E, before going on a 200 mile trip to visit her mother. When she got back home, she said the motor smelled funny, and the motor was smoking.
When I opened the hood, I saw she forgot to put the oil cap back on...
There was oil dripping down the motor. A few days later, the blinker, the fan blower, and the radio stopped working, then the engine ran rough for a few seconds then just died.
I jumpped it and got it running for a little while, but then it died again.
I noticed the alternator has oil ALL over it.
Is there a chance that oil could short it out?
Can I just degrease it and be OK?
Has anyone ever had this happen?
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1996 S420 (45,00O)
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1988 190D (125,000) sold
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  #2  
Old 02-06-2009, 11:57 PM
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wow...that's whack...i don't even know what to say about that one....damn.....
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  #3  
Old 02-07-2009, 12:05 AM
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Rule #1: Wife never allowed to open the hood again.

I wonder how much dirt and junk got in there from 200 miles of cap free driving!! I'd be changing the oil ASAP!!

Rule #2: Wife not allowed to open the hood.


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  #4  
Old 02-07-2009, 07:06 PM
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I'd first ask her to see how much oil she added. If she knows what she's doing, then fine...

if not, its like I tell most women, don't touch anything under the hood or the hood release!

Okay. Yes, motor oil conducts electricity like most other natural oils-even synthetics (I think).

I second the post above. Change the oil ASAP. Then flush it... I'd consider running it for as long as it'll run, then changing the oil again checking the dipstick all in between for oil consistency. I personally would drop the oil pain in between flushes to scrape out whatever comes out (if anything).

I would get it sprayed down. An carwash place should be able to do this for you. Then of course you can start it and run it to see where the leak is coming from if that's the case. With regard to the electrical issues, I really must say that's also my worst fear. It definitely is a short, but your best bet is to follow the traces of oil splatter. Keep in mind that an open oil cap will allow a lot of oil to splash out because of the exposed rocker arms and cam lobes.

Good luck,

-Troy
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  #5  
Old 02-07-2009, 07:09 PM
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Just thought I'd mention. Check your fuses just in case. I don't know the 300e, but those devices could all be on the same circuit. If its blown, get the engine cleaned and replace the fuse to see if it blows again.
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  #6  
Old 02-07-2009, 07:33 PM
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This is a thing that happens with the w124s; the alternator is so low that the oil CAN drip into it and cause a failure. Time for a new one!
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  #7  
Old 02-07-2009, 07:40 PM
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Schettini, if you haven't already check the oil level to confirm how much oil discharged from the engine while running without the oil fill cap. I would be more concerned about how much oil discharged from the engine than some dust entering through the open oil fill hole. If the oil level got too low it's possible there is major engine damage. Add oil, as required, so the level is at the midpoint on the dipstick gauge. Did any of the dashboard trouble lights come on while your wife was driving, or did the engine overheat? As for the alternator I would spray it with brake cleaner to clean off as much oil as possible. The engine is likely stalling out because the alternator is not recharging the battery. Consider replacing the voltage regulator which attaches to the back of the alternator with 2 screws, or at least remove it and clean the brushes and the armature. It's possible you will need to disassemble the alternator to clean it properly. Inspect the spark plug recesses to make sure they aren't partially filled with oil, and check that the distributor cap is dry and oil-free. Good luck.
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  #8  
Old 02-07-2009, 08:53 PM
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Oil is an insulator. It won't cause shorts. But it can coat the alternator slip rings and brushes. It can also cause the alternator drive belt to slip. The alternator can be cleaned with Brakleen but there is a chance of washing grease out of the bearings, so use care.
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  #9  
Old 02-07-2009, 10:38 PM
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truth all of the above.....this is why i watch the wifes 1990 300TE like a hawk for everything. i want to make sure that there is no reason for her to go up in there and start trying to add stuff. fuel is ok, as is the rule here; i don't even want to talk about windshield wiper fluid...tell me it's low and i will take care of that right now. you think you need air in the tires? fine..i'll go take of that right now...saves me aggravation in the long run i think....
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  #10  
Old 02-08-2009, 03:32 AM
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So where did she leave the oil cap? Could it have fallen into the belt drive system when the engine was running?
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  #11  
Old 02-08-2009, 04:01 AM
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Quote:
Originally Posted by cliffmac View Post
truth all of the above.....this is why i watch the wifes 1990 300TE like a hawk for everything. i want to make sure that there is no reason for her to go up in there and start trying to add stuff. fuel is ok, as is the rule here; i don't even want to talk about windshield wiper fluid...tell me it's low and i will take care of that right now. you think you need air in the tires? fine..i'll go take of that right now...saves me aggravation in the long run i think....
Same here. My wife does know what to do to add fluids and such....but I keep so on top of it that she never has reason to open the hood. She'll let me know if the low oil level lamp blinks at her....then I go add some. Same for washer fluid etc.... I check it once a week usually....so she really never needs to open it up. Which is good. I like being the only person messing around in there.

On a gasser driving with that cap off = Vacuum into engine, aka dirt and air likely sucked in. (unless the motor has some blowby) The M103 doesn't seem to spit out much oil with the cap off.....since the oiling system is kinda self contained in the camshaft....

I'd still be changing that oil right away!!!
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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 75k - mine - (OC-80,500)
'17 Metris(VITO!) - 6k - wifes (OC-10k)
'01 E320 Wagon - 157k - mine (OC-160,000)
'89 420SEL 166k - mine (OC-167,000)
'01 E320 - 167k - dad's (OC-171,500)
'07 E350 Wagon - 130k - dad's (OC-132,500)
'01 SL500 - 48k - dad's (OC-52,000)
'09 E350 4matic Sedan - 123k - Brothers (OC-127,000)
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  #12  
Old 02-08-2009, 04:55 PM
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Well at least she knew to put in the oil and where to put it so I give her half credit for that. Some people don't know that much. I have forgotten caps before... Basically everything has been said, check the oil level. As far as the alternator you could do a voltage test. When running should be at about 13.9 to 14.4 I think.
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